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J>R. DICKIE ON GEBMINATION. V27 



About the middle of the summer of 1864, having beside mc a 

 few seedlings of the castor-oil i)lant, I pinched off the phunule in 

 several ; subsequent attempts at the formation of a new axis and 

 leaves required the operation to be repeated, after which the co- 

 tyledons alone remained and increased to nearly double the ordi- 

 nary dimensions, the axis which supported them growing also in 

 length and diameter. The plants so treated continued to live for 

 three months, and would doubtless have survived longer ; but, 

 owing to neglect, they were injured by attacks of insects, and 

 after some time decayed ; the result, however^ was so far satisfac- 

 tory, since the life of the cotyledons was extended far beyond 



the existence of these organs iu plants left to run the ordinary 

 course. 



The next experhnent, towards the end of July 1864, was made 

 on a species of Ipoma^a : the large foliaceous cotyledons I con- 

 sidered as rather an advantage for my purpose. Tlie plumule in 

 one plant was pinched, and, as in the former case, the operation 

 required to be repeated ; another individual was left uninjured, for 

 the sake of comparison, and at the end of three months it had 

 produced abundance of leaves, with shoots of 12 to 18 inches in 

 length, and a fcAv flower-buds, which, owing to want of suflScient 

 ^^ght, dropped off, as did the cotyledons, about the end of two 

 weeks after germination. The other plant which had been pinched 

 continued to live for more tlian three, months, the cotyledons 

 remaining fresh and green and attaining a larger size than under 

 ordinary conditions. Owing to the unfavourable period of the 



m, at the end of the time mentioned, to 

 assume an unhealthy appearance, and, as the phrase is, they 

 ultimately " damped off." The axis of the mutilated plant made 

 .quite as rapid progress as that of the other below the scars of the 

 cotyledons, and at the end of the experiment the two were about 

 equal in diameter. 

 - It is my intention to commence a new set of experiments, and, 



of the 



under 



year. 



There are certain obvious precautions necessary in this matter, 

 such as careful inspection of cotyledons in order to prevent in- 

 jury from insects or mould, and due moderation in supplies of 



care is rec^uisite in handling the cotyledons. 



great 



